1. Field
Various exemplary embodiments relate to a directional backlight unit having an improved light spreading capability, an image display apparatus including the directional backlight unit, and a method for manufacturing the directional backlight unit.
2. Description of the Related Art
To overcome the limitation of displaying only two-dimensional (2D) images without depth information in traditional image display apparatuses, techniques related to three-dimensional (3D) image display apparatuses have been studied intensively. A main type of currently commercialized 3D image display apparatuses uses bionocular parallax, in which a left-eye image and a right-eye image having different viewpoints are provided to a left eye and a right eye of a viewer, thereby enabling the viewer to feel a cubic effect. The 3D image display apparatuses may be classified into glasses-type 3D image display apparatuses requiring special glasses and non-glasses-type 3D image display apparatuses that do not require glasses.
The glasses-type 3D image display apparatuses use a red-green glasses type for movie theaters and use a polarized-glass type or a liquid crystal shutter type for televisions (TVs). The non-glasses-type 3D image display apparatuses are classified into a barrier type and a lenticular type based on their structures, and are classified into a multiview rendering type, a volumetric type that contains all information of a 3D space and expresses the information on the 3D space in the form of voxels, an integral imaging type that captures images from various angles, which are focused through compound eye (i.e., fly's eye) lenses of insects, and displays the images inversely, a holographic type, and so forth, based on their image implementation types.
The non-glasses-type 3D image display apparatus using a directional backlight unit uses a grating having a size of several hundreds of nanometers in terms of a structure, and sets the direction of light emission to a desired direction by selecting one of the aforementioned image implementation types, thus implementing a 3D image.